1. Field of the Invention
The present invention relates generally to the field of software compilation, and more particularly to the field of mixed language software compilation toward software implementation, hardware implementation, or both.
2. Description of the Related Art
In the software programming field, there are numerous programming languages optimized for different purposes. For example, the object-oriented programming languages (OOPLs) are the natural choice for implementation of an Object-Oriented Design because they support the object notions of classes, inheritance, information hiding, and dynamic binding. Currently available OOPLs include C++, Objective C, Smalltalk, Eiffel, Common LISP Object System (CLOS), Object Pascal, Java, and Ada 95.
Object-oriented (OO) applications can be written in either conventional languages or OOPLs, but they are much easier to write in languages especially designed for OO programming. OO languages can be divided into two categories, hybrid languages and pure OO languages. Hybrid languages are based on some non-OO model that has been enhanced with OO concepts. C++ (a superset of non-OO language C), Ada 95, and CLOS (an object-enhanced version of LISP) are hybrid languages. Pure OO languages are based entirely on OO principles; Smalltalk, Java, and Simula are pure OO languages.
Another available computer language type is a distributed programming language that supports Internet-based applications. Several new languages now available, such as Java, Phantom, and Python, attempt to provide Internet- or Web-optimized solutions. All of these languages provide some degree of network support. However, equally important is that all of the distributed programming languages that support Web applications also support general programming tasks, which constitute the bulk of Web-related programming. Distributed programming languages also qualify as object-oriented, since they enable sub-typing, polymorphism, inheritance and dynamic binding.
Also, distributed programming languages are interpreted, which makes them largely platform independent and allows the user to migrate programs and objects more easily from location to location. Phantom, and Python are pure distributed programming languages but can be difficult to compile. Java shares the strengths of the other distributed language, but can be more efficiently compiled. Thus, Java is a hybrid distributed programming language because it is based on a non-Web model that has been enhanced with Web concepts.
Another category of programs are hardware description languages (HDL) that specify design behavior. Some hardware description languages are intended for a particular type of behavior. For example, Esterel is a language designed for control-oriented behavior, while Lustre and Signal are optimized for data-oriented behavior. It should be noted that, while Esterel is an outstanding language for hardware description, it was originally written for pure software applications and continues to be used as such. As with other language types, hardware description languages may be hybridized to enhance functionality.
One candidate for producing a hybrid language for hardware descriptive purposes is the language C. While C alone can be inefficient for pure hardware design work, since the design flow might lack certain key tools and capabilities, C is widely used and the overhead saved in choosing a widely-known language can be considerable.
Thus, in the available art, there are several published languages for specification of system-level mixed hardware/software designs, which are commonly conceived as interacting, concurrent modules. The available art languages provide mechanisms for specifying both the computation of each module and the communication and coordination between them. The available art languages can be summarized as follows.
1. A host language is used for describing the computation of each process and a coordination language is used for describing concurrency and interprocess communication. For reference, please, see “Design of embedded systems: formal models, validation, and synthesis”, by S. Edwards, L. Lavagno, E. A. Lee, and A. Sangiovanni-Vincentelli, published in the Proceedings of the IEEE, 85(3), 366-390, March 1997, included herein by reference. A disadvantage of this approach is that the burden of deciding what is coordination and what is computation is left to the user and is fixed, a priori, by the language choice even though the definition is often quite blurred. An advantage is that the compilation algorithms for computation and coordination can be made very efficient.
2. A single language is defined with a single compilation algorithm. A problem with this approach is that it is difficult to best exploit all the potential interplay between concurrency, control and sequencing with a single general-purpose compiler. Traditional software compilation focuses mostly on extracting local parallelism and executing local optimizations, while concurrency compilation focuses mostly on global scheduling.
There is therefore a need in the art for a language, and an associated compiling technique, that combines the advantages of a plurality of existing languages to provide system level designers with a tool powerful enough to support efficient specification of control and data, globally optimized compilation to hardware and software, and that includes semantics and well-developed accompanying compilers and development tool sites familiar enough to the installed base of users to enable rapid, widespread adoption.